For years I have used Stabil brand gasoline stabilizer in the tank. I've heard that with the increased alcohol level in gasoline, one should run the tank dry as the alcohol will pull water from the atmosphere over time.

Naturally, you'll want to scrape the grass from the inside of the housing, after removing the spark plug wire. Now is a good time to get the blade sharpened if it needs it. Wear leather gloves when working around a sharp blade!

Next change the oil, if a 4 cycle mower. Use the right grade of oil per the manufacturer. The air cleaner should also be cleaned if foam or replaced if it is a paper element. To clean a foam air cleaner, wash it out in soap and water,rinse, then squirt in a teaspoon of motor oil and work it thoroughly to distribute the oil. Recycle the used oil to a local garage or recycling center if your community has one - never pour it down a drain or put it in the trash.

Remove the spark plug and examine it for wear and deposits. If it is all crusted up, replace it with the same number plug. Do not over tighten the new one.

Rather than put a gas stabilizer in the gas tank, I just run my snow blower until it runs out of gas. That ensures that there's essentially no fuel in the machine that needs to be stabilized over the summer months.

Also, for those that are interested, the way to tell if your lawn mower blade needs sharpening is by the tops of the grass blades. A sharp blade will CUT cleanly through the blades of grass, and that doesn't do nearly as much damage as bashing through the blade with sufficient force to tear it into two pieces the way a dull blade will. The result is that if you have a dull blade on your mower, the tops of each blade of grass will have a dead "tip" that will be beige in colour (which is typically be the same beige colour as dead grass). So, if you see that your grass has beige tips on the top of each blade, it's a sure sign that your mower blade is dull and needs sharpening.

(The analogy would be that having an arm surgically amputated causes far less damage to it than having the same thing done accidentally by an airplane propeller.)

On my electric lawn mower, the bolt (or nut) holding the blade onto the motor shaft is a normal right hand thread. My understanding is that this is standard, and that all lawn mowers will have a standard right hand thread bolt or nut holding the blade on, so you remove the blade for sharpening by turning the bolt or nut counter clockwise (when viewed from below the lawn mower) to remove the blade. As previously noted, remove the spark plug wire from the spark plug before attempting to remove the blade. There's a slim, but non-zero, chance that the lawnmower could start if the motor crank shaft is turned by someone trying to remove the mower's blade. Removing the spark plug eliminates the miniscule possibility of the mower starting. It's not likely to happen, but the consequences of the lawn mower motor starting while you have your hands in the plane of rotation of the blade is severed enough to warrent removing the spark plug wire to eliminate that possibility completely.

Rather than put a gas stabilizer in the gas tank, I just run my snow blower until it runs out of gas. That ensures that there's essentially no fuel in the machine that needs to be stabilized over the summer months..........<snip>.............

Right. In the past, some rubber diaphragms in carburetors would dry out if stored with no fuel, thus the need for stabilized gasoline. Something to be on the look out for..............

I run mine out of fuel and fog the chambers/cylinders with wd40.
Boats also have a big issue every year with gas. Mercury has tackled that issue pretty good with their staybilizer if that is the route you take.
My snowmobiles and kids go carts act up even when you run them out of gas after a few years. Takin the carb apart to clean it is something everyone should do once, it's really easy.

I run mine out of fuel and fog the chambers/cylinders with wd40.
Boats also have a big issue every year with gas. Mercury has tackled that issue pretty good with their staybilizer if that is the route you take.
My snowmobiles and kids go carts act up even when you run them out of gas after a few years. Takin the carb apart to clean it is something everyone should do once, it's really easy.

Right. In the past, some rubber diaphragms in carburetors would dry out if stored with no fuel, thus the need for stabilized gasoline. Something to be on the look out for..............

I was told that leaving fuel in the carburetor over the summer (or winter) could result in some kind of gunk forming in the carburetor. So, I just let the snow blower run out of fuel so that there's no fuel in there to form any gunk.

Was I misinformed, or have I just been lucky not having had problems until now doing that? So far, I've been doing it for over 20 years, and haven't had any fuel system problems at all.

I was told that leaving fuel in the carburetor over the summer (or winter) could result in some kind of gunk forming in the carburetor. So, I just let the snow blower run out of fuel so that there's no fuel in there to form any gunk.

Was I misinformed, or have I just been lucky not having had problems until now doing that? So far, I've been doing it for over 20 years, and haven't had any fuel system problems at all.

Nestor, I'm going on anecdotal evidence. I'm a mechanical engineer, but you have a much better chemistry background. My guess is that the "rubber" parts used in carburetors vary in makeup such that some are more resistant to alcohol, old gas, drying out, etc. I have also heard of gaskets drying out and shrinking - again depending on the material used.

I put myself through college fixing small engines, but that was over 30 years ago, so much of what I observed may be obsolete. The product Stabil is supposed to keep gasoline from breaking down into the "gunk" that you refer to and in the past, I've had excellent luck with it. That said, I've heard complaints of new problems with the current 10% alcohol in gasoline.

My small engine guys is putting his kids through college due to the mandated Ethanol in gas!! Its killing small engines.

I run the engines dry and put them away. I do the sharpening, oil change, etc in the spring. Oh, and pour any gas left in the gas can into the car. Don't save it for spring. Ethanol will cause the gas to go stale pretty quick.